Vocal cord movement -- can it be accurately graded?

Abstract

Background: Flexible nasendoscopy is the principle method of assessment of vocal cord movement. As this procedure is inherently subjective it may be that it is not possible for clinicians to grade degree of vocal cord movement reliably. Aim: The aim of this study was to assess the accuracy and consistency of grading of vocal cord movement viewed via flexible nasendoscopy. Design: Prospective video analysis study. Methods: Thirty flexible nasendoscopy videos, without sound or clinical information, were assessed by 6 consultant Head and Neck surgeons. They were asked to assess and grade right and left vocal cord movement independently, based on a 5-category scale. This process was repeated three times at separate time intervals. Agreement and reliability were assessed. Participants: 6 consultant head and neck surgeons. Results: The mean overall percentage of observed inter-rater agreement was 67.7% (SD 1.9) with the 5-categories scale, increasing to 91.4% ( SD 1.9) when a 3-category scale was derived. The mean overall percentage of observed intra-rater agreement was 78.3% (SD 9.7) for 5 categories, increasing to 93.1% (SD 3.3) for 3 categories. Discriminating vocal cord motion using the 5-category scale is less reliable (k= 0.52) than with the 3-category scale (k = 0.68). Conclusion: This study demonstrates quantitatively that it is challenging to accurately and consistently grade subtle differences of vocal cord movement as proven by lesser agreement and reliability when using a 5 point scale instead of a 3 point scale. It highlights the need to have an objective measure to help in the assessment of vocal cord movement.